Emperor
penguin diving under ice

Emperor penguins feed on fish, krill and squid which
they catch on dives that are longer and deeper than any other penguin
or bird species. They can dive to a depth of 1,800 feet (550 meters)
and hold their breath for up to 22 minutes. This allows them to reach
and exploit food resources that other birds can't.

The diving abilities of emperor penguins has been
widely studied, they have been found to have:

1/ an increased ability to store oxygen in the body
2) the ability to tolerate low levels of oxygen in the body3) the
ability to tolerate the effects of pressure